How to realign Xbox 360 S disc tray?

The disc tray is stuck and won't open unless I push it up a little bit then press the eject button, after doing that it closes and ejects just fine, without pushing it up with my hand. What is causing this problem? Absolutely nothing hit the disc tray and it just suddenly start doing that, could the disc tray be misaligned? If so how can I permanently realign it?